The invention relates to dispensing rolled flexible sheet material such as paper towels, toilet tissue and like rolls wherein each roll has a hollow central core and is mounted on support means provided within the dispenser. More particularly, the invention herein is concerned with dispensers capable of handling multiple source rolls of sheet material wherein occasion will arise for several plies of material to be jointly cut or severed in dispensing cut web sections successively from the dispenser.
Where dispensers of paper toweling in roll form are used, the dispenser is generally mounted on a wall in a location where towel availability is desired. Large numbers of such dispensers are employed in installations such factories, office buildings, institutions, etc. Substantial time and expense can be required by personnel servicing large numbers of dispensers in replenishing the exhausted wound rolls in such dispensers. This gives rise to the increasing importance of providing reliably operable multiple roll material dispensers where, upon exhaustion of material from a roll located within the dispenser at an initial or dispensing position, the web end from a reserve roll within the dispenser will effectively be picked up and fed into the dispensing mechanism to be supplied to the intending towel user. These dispensing mechanisms frequently include a perforating or severing mechanism by means of which the web material coming from the roll can be perforated or severed into individual sheets that are then fed out of the dispenser.
Also, in multiple roll dispensers for sheet material it has been known in the prior art to utilize a limited remaining portion of web material on a nearly depleted or exhausted initial roll as a convenient guide to lead the web end from a full reserve roll into the dispensing mechanism. This easily and effectively assures that the web end from the reserve roll passes into the dispensing mechanism and thence out of the dispenser to the intending user. Where this technique is employed, several plies of material will be fed from the dispenser for a limited number of cut sheet dispensing cycles, one ply coming from the nearly exhausted or depleted roll of material and the other ply coming from the fresh full reserve roll that has remained unused it the dispenser housing while the web material from the initial roll was being dispensed.
Examples of rolled flexible sheet material dispensers capable of handling multiple rolls and wherein several plies of material are fed from multiple source rolls during a limited period when a nearly exhausted or depleted roll is being replaced by start up of material taken from a full fresh reserve roll may be found in DeLuca et al U.S. Pat. No. 4,137,805 issued Feb. 6, 1979 and Jespersen U.S. Pat. No. 4,236,679 issued Dec. 2, 1980. In the multiple roll material dispenser concepts of each of these patents the changeover from dispensing web material from the nearly exhausted first roll to taking web material from the reserve roll that had been retained in the dispenser involves feeding several plies from the multiple source rolls through the dispensing mechanism out of the dispenser to the intending user. In each, the primary source roll from which the continuing web material will be supplied into the dispensing mechanism is supported to rest on a feed roller which is part of the dispensing mechanism.
A further characteristic of the type dispenser with which this invention is concerned and which is exemplified by the two above-identified patents, is that the other source from which web material has been dispensed to substantially exhaust the other source roll is separately rotatably supported during the limited internal period until the web material is fully exhausted from this other roll. In its fully exhausted or depleted state, the core of the other source roll remains in the dispenser in a discard position awaiting the service attendant's attention in reloading the dispenser with a fresh full source roll. Of course such reloading in the multiple roll material dispensers contemplated for this invention need not be undertaken until the multiple source rolls within the dispenser are totally depleted or exhausted of web material, leaving only the cores of the source rolls in the dispenser.
In the above-described type of dispensers for cut-web dispensing, it may be necessary, at least for a limited number of dispensing cycles to cut and dispense two plies of web material such as toweling. These few dispensing cycles, normally only about 10 to 14 cycles in dispensing cut individual sheets, occurs at the point whereat transfer occurs between dispensing the web material from the initial source roll that has become nearly depleted to pick up and subsequent dispensing from the reserve roll. During this transfer interval, the main source roll which is to take over supply of web material to the dispensing mechanism rests upon the feed roller with the other source roll, now nearly depleted or exhausted, supported off of or out of engagement with the feed roller while still having the web remaining on this other roll core passing over the same feed roller.
In the above-described circumstances where it is necessary to sever two layered plies of web material from two or more separate source rolls, a problem has been encountered by reason of the tendency of the two web plies to slip relative to one another when the cutting means which carries out the cut-web dispensing action is pushed through these layered plies of web material. This slippage problem may occur whether the cutting means is carried internally of the feed roller such as is characteristic in the dispensing mechanism of DeLuca U.S. Pat. No. 4,188,844 issued Feb. 19, 1980 or where the cutting means is pushed through the layered plies of web material from the exterior of the feed roller.
The problem of relative slippage between several plies of material which are being fed to a dispenser cutting mechanism from multiple source rolls must be dealt with to ensure effective cut-web dispensing of individual sheets from the multiple roll dispenser. Considering the conditions for a dispenser having a cutter mechanism in the form of a cutter-containing feed roller as disclosed in U.S. Pat. No. 4,188,844, the web of material coming from the nearly exhausted or depleted source roll which is rotatably supported off to the side of the feed roller, still passes over this feed roller. For optimum cutting, the feed roller is surfaced with a high friction material to keep this web from slipping relative to the feed roller not only to effectively drive the roller when the web is pulled out of the dispenser by the intending user, but also to prevent slippage of the web relative to the feed roller when the cutting knife is moved outwardly from the feed roller interior in performing the cutting action.
Preferably the cutting knife is provided with a serrated edge and when the points of the cutting knife first penetrate the web coming from the nearly exhausted or depleted source roll they are effective in penetrating and cutting this web but where a second web coming from the main source roll which is resting on the feed roller is present, the cutting knife tends to move this second web outwardly from the web which is in contact with the feed roller. At this stage, the knife does not fully cut this second web unless some means is provided to prevent slippage between the two webs that are being jointly dispensed in passing over the feed roller during the transfer interval that exhausts web material from the initial roll and picks up web material from the new source roll that was held in reserve.
The slippage between these several plies of web material comes about by reason of the difference in the coefficient of friction between the web resting on the high friction surface of the feed roller versus the coefficient of friction between the second web from the new source roll and which is only in surface contact with the web coming from the nearly exhausted source roll. Generally, it is found that the coefficient of friction between the several web plies is about two-thirds the coefficient of friction between the web and the high friction surface of the feed roller with which it engages.